The purpose of this investigation is to evaluate the application of a direct current to stimulate bone ingrowth into porous aluminum oxide. Porous cylindrical samples have been implanted into the medullary canal of canine femora, both in the cancellous and cortical bone regions. Constant current (10 micro amperes) power packs are implanted on one side and maintain the implant site at a relative negative potential with respect to the surrounding soft tissue. The contralateral side is used as a non electrically stimulated control. A second series of implants having either a 50 micro amperes, 100 micro amperes or 200 micro amperes constant current power pack have been evaluated. Tissue ingrowth is evaluated using a mechanical push-out test, microradiography and histological thin sectioning. A protocol has been established whereby each method of evaluation can be performed on each implant. The interfacial shear strength and tissue microstructure are studied as a function of implant residence site and time. The results indicate that initially the proximal implants have a higher interfacial shear strength; however, after eight weeks of implantation the distal implants have a shear strength about twice that of the proximal implants. This trend is observed for both the electrically stimulated and non-stimulated specimens. The 10 micro amperes current level used in this investigation was found to have a small but significant effect on shear strength, increasing it at implantation times of less than eight weeks.